Discovery of Human Gut Bacteria Responsible for Biotransformation and Structural Diversification of Oat Steroidal Saponins
Year: 2026
Type: article
Abstract: Oat steroidal saponins undergo biotransformation by the gut microbiota, yet the bacteria involved and the structural diversity of the resulting metabolites remain incompletely characterized. Incubation of avenacoside B (AVE-B), a major oat steroidal saponin, with fecal microbiota from six human donors revealed marked interindividual variation in avenacoside E (AVE-E) production. Five bacterial species capable of AVE-B metabolism were isolated, with Bacteroides uniformis SS-F-0001 exhibiting the broadest metabolic profile. Quantitative PCR and carbohydrate-active enzyme profiling suggested that abundance alone did not explain conversion capacity. Comparative 1D and 2D NMR analysis of isolated AVE-E and its isomer revealed diagnostic C-22 and C-25 chemical-shift differences and H2-26 → C-22 HMBC correlations, supporting an isonuatigenin-type isomer with a six-membered F ring. These findings identify bacterial contributors to oat saponin metabolism and reveal structural diversity involving both deglycosylation and aglycone ring rearrangement, providing a basis for investigating the mechanisms and biological consequences of microbial saponin metabolism.
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W7225754678